There is a lot of confusion about testing requirements for passengers of cruise ships. Regardless what governments around the world implement or if they relax restrictions for covid 19, cruise lines have their own protocols for passengers and crew. Here is a list of different cruise lines and their protocols:

https://www.travelandleisure.com/cruises/cruises-that-allow-vaccinated-travelers

So it looks like testing is a go no matter what governments require.